Hydraulic buffer



May 15, 1962 H. M. PERNINI HYDRAULIC BUFFER 2 Sheets-Sheet 1 Filed March 14, 1961 mmf m .Sm

INVENTOR. HENRY M. PERNINI May 15, 1962 H. M. PERNINI HYDRAULIC BUFFER 2 Sheets-Sheet 2 Filed March 14, 1961 INVENTOR.

H ENRY M. PERN I N l il wa, a. J. @410ml @5mg/Q.

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Patented May 15, 1962 3,034,605 HYDRAULIC BR Henry M. Pernini, Chicago, Ill., assignor, by mestre assignments, to the United States of America as represented by the Secretary ot the Army Filed Mar. 14, 1961, Ser. No. 95,749 5 Claims. (Cl. 18S-96) The present invention relates to a shock absorbing mechanism and more particularly to a hydraulic type buffer which is useful with ordnance items and wherein the buffer action is limited to a relatively short interval in the over-all movement thereby permitting a reciprocating member to travel with a minimum of resistance throughout a substantial portion of its movement.

Although various means for buffering a pressure actuated reciprocating member have been proposed heretofore, the means customarily relied upon has been the compression of a spring which returns the reciprocating member to a normal position. For some applications, it is desirable not only to buifer the member in the initial direction of travel, but also in the opposite or return direction of travel. In such cases, apart from the return spring buffering the action in the initial direction of travel, a separate buler is employed to absorb the forces incident to return of the reciprocating member to its normal position. While arrangements of this kind are suitable for most applications, they are objectionable from the standpoint that they offer not only resistance to the initial stroke or movement of the reciprocating member, but also resistance to a substantial portion of the return or counterstroke movement, as well as adding materially to the weight of the apparatus with which they are associated.

Therefore, it is a primary object of the present invention to provide an improved hydraulic type buffer for a reciprocating member which will limit the buer action to a relatively short interval of the over-all eifective movement of the member.

Another object of the present invention is to provide an improved hydraulic type buifer which will enable the associated reciprocating member to operate with a minimum of resistance.

It is also an object of the present invention to provide a reciprocating member with an improved butter which is relatively ineffective upon the member traveling in the one direction but is eifective in the opposite direction of travel for a relatively short interval thereof.

A further object of the present invention is to provide buffer means for an operating slide, such as employed in ordnance equipment, wherein the buffer action during the return to normal stroke is limited to a relatively short interval at the end of the stroke.

Still further it is an object of the present invention to provide a buffer for ordnance equipment which will permit maximum freedom of travel of a reciprocating member while buffering its movement in opposite directions of travel.

An additional object of the present invention is to provide buler means for absorbing the shock o-f a gun slide coming into battery position without producing energy losses during other parts of the operating cycle.

Also it is an object of the present invention to provide a hydraulic buffer which is suitable to ordnance equipment and which is simple in construction and positive and reliable in operation.

In accordance with the present invention a hydraulic buffer is provided for buffering the counterstroke action of a recuperator for the slide of a gun. The bulfer comprises a stationary cylinder and a piston which operates in a uid medium. The buffer is telescopically arranged about the rod connecting the gun recoil slides with a gas operated piston of the recuperator. The structural arrangement is such that the gas piston rod slides axially through the buffer for a substanital portion of its travel during its initial stroke before it picks up the buffer piston; Again, in counterstroke, the gas piston rod travels a substantial portion of its distance before it picks up the buffer piston. The butter piston is arranged so that, in the initial movement it is substantially free but, in return movement, it functions with a dashpot effect to buffer the counterstroke forces during the last small portion of counterstroke travel.

The novel features characteristic of the present invention, as well as additional objects and advantages thereof, will be understood better from the following detailed description when read in connection with the accompanying drawings. The drawings presented depict a series of steps in the operation of a recuperator for a gun which is provided with a buifer in accordance with the present invention. The series comprises various steps from the initial battery position, through the initial stroke or movement in the one direction and return thereof in the opposite direction to the batt-ery position, and, in which:

FIGURE 1 shows a central longitudinal View in cross section of the recuperator embodying the present invention, the parts being shown in a normal, battery position;

FIGURE 2 is a View similar to FIGURE l, the parts thereof being shown at the stage during the initial stroke when the gas piston rod engages the butter piston rod;

FIGURE 3 is another View similar to FIGURE l wherein the parts are shown with the buifer piston rod advanced by the gas piston rod into engagement with the floatin piston of the buffer;

FIGURE 4 is the next view in the series, wherein the parts are shown at the limit of the initial stroke;

FIGURE 5 is the first step in counterstroke movement and wherein the gas piston rod is engaged with the buler piston rod just prior to etecting buffer action; and

FIGURE 6 is the next step incident to eifecting buer action, the parts being shown with the lloating piston parts closed ready to buffer the counterstroke forces.

Referring more particularly to the drawings wherein similar reference characters are used to designate corresponding parts throughout, a singleJ preferred embodiment of the present invention is shown as applied to the recuperator of a gun.

The present invention contemplates the use of a butter 1 for buffering the counterstroke forces of the recuperator. The buffer comprises a cylinder 3, a piston 5 operative in a fluid medium '7, and a piston rod 9'.

The recuperator members with which the buffer is operatively associated comprise a gas cylinder 11, a gas piston 13, and a piston rod 15. The purpose of this gas piston and cylinder is to operate a slide 17 member which is utilized in an automatic system of a `gun for effecting a mechanical movement or operation. The system is effective when the gun is red by virtue of the gas piston 13 being responsive to the expanding gases incident to firing. The expanded gases are applied through a port 19 in the cylinder wall 21 to cause the kgas piston and the piston rod '15 attached thereto to move axially to the left as viewed in the drawings, in a manner well known in the art. The gas piston rod is, in turn, connected with the slide body member 17 so that the slide is operative simultaneously with the gas piston rod. Mounted securely within the gas cylinder 11 adjacent to the end thereof which is opposite to that to which the expanding gases are introduced, is an end wall 23. The gas piston rod 15 extends through a central opening 25 in this end wall andis freely supported thereby for axial movement. A coil spring 27 is disposed between the end wall 23 and the piston 13. The coil spring encompasses the gas piston rod and serves under compression to return the piston to a normal battery position after the recuperator has completed its initial stroke in the cycle of operation. For the purpose of exhausting the expanding gases from the gas cylinder after the initial stroke has been completed, an exhaust port 29 is provided in the cylinder wall at a point which would be in front of the piston at its full initial stroke position, as more particularly observed in FIGURE 4 of the drawings. In order to provide pressure relief in that portion of the gas cylinder occupied by the return coil spring 27, one or more openings 31 are provided through the cylinder wall at any convenient location.

The buffer of the present invention is disposed between the gas cylinder and the slide body member in a manner to surround the gas piston rod 15. The cylinder housing 3 is threaded at both ends complementary with threaded ends respectively of the gas cylinder 11 and a housing 33 for the slide body member 17, so that all three members, being attached together, provide a stationary housing when attached to the gun. A hollow cylindrical piston rod 9 is telescopically mounted on the gas piston rod and is disposed between the cylinder housing 3 and a rod-like portion of the gas piston rod 15. The buffer piston rod 9 is provided with a stepped bore of two different diameters. The small diameter bore 35 constitutes a relatively small portion of the over-all length of the buffer piston rod at the end thereof adjacent to the slide body member. The size of this small diameter portion is such that it is slidably disposed on the gas piston rod 15. The larger diameter portion 37 of the buler piston rod 9 is greater in diameter than the outside diameter of the gas piston rod so that it is disposed in spaced relation thereto thereby to accommodate an outwardly extending flange or shoulder 39 provided on the gas piston rod for freedom of movement axially. The length of the chamber or space 41 formed between the buffer piston rod and the gas piston rod should be of a size that it will permit the gas piston rod llange 39 to travel all but a relatively small portion of its over-all travel in the initial stroke before it engages a shoulder 43' of the butler piston rod formed between the two different diameter inner surfaces.

Inasmuch as the buffer is of the hydraulic type, a bulkhead or closure member 45 is provided for the buffer cylinder 3 adjacent to the end thereof which is remote from the gas cylinder. The closure member 45 surrounds the buffer piston rod and is freely slidable on the buffer piston rod although it is in iluid-tight relation with both the buffer piston rod and the cylinder wall. The opposite end of the cylinder is of reduced diameter so that it slidably receives the buffer piston rod but in iluid-tight relation therewith.

The buffer piston rod 9 carries a floating piston 5 which is annular and mounted externally on the rod for slidable movement axially thereof. The lloating piston has an outwardly extending llange 47 disposed on the end remote from the gas cylinder 1l. The flange 47 extends substantially to the inner wall 49 of the bulfer cylinder w1th the circumferential edge thereof slightly tapered. Thus, the floating piston eectively divides the chamber into two compartments. A plurality of apertures 51 are provided through the piston flange which permits the passage of a iluid therethrough. The axial movement of the floating piston on the piston rod is restricted to some extent by being disposed between two annular outwardly extending flanges 53, 55 provided on the butler piston rod 9. The flange 53 disposed adjacent to the piston flange 47 extends outwardly a distance at least coextensive with the openings 51 so that when the buffer piston rod llange 53 abuts the lloating piston ilange 47, the openings are closed and the llow of iluid therethrough will be impeded. Thus, the flange 53 and the apertures 51 function as a one-way valve so that the floating piston 5 oiers substantially no resistance in the initial stroke and effectively infinite resistance in the counterstroke. In order to facilitate the dashpot action of the hydraulic buffer, a portion of the cylinder wall 49 in the vicinity of the floating piston is tapered outwardly in the direction of initial stroke of the recuperator.

The chamber 57 provided by the buffer cylinder 3 surrounding the buffer piston rod 9 is filled with a suitable fluid medium 7. The bulkhead `45 being freely disposed around the buffer piston rod, is provided with a valve 59 for bleeding the lluid chamber. In addition thereto, a coil spring 61 is disposed around the end of the bulfer piston rod which extends beyond the bulkhead. Once the buffer chamber is filled with a iluid and the parts assembled, the spring -61 is maintained under compression so that the bulkhead is forced against the iluid thereby to keep the chamber thoroughly filled with the fluid.

The above described arrangement will be found to operate as follows. When the weapon is fired, the expanding gun gasses act upon the gas piston 13 forcing it to negotiate the initial stroke to the left, as viewed in the drawings. Inasmuch as the gas piston rod 15 is connected to the gas piston, it too will move the left and, after completing a substantial distance of its travel in negotiating the initial stroke, it will pick up the buffer piston rod 9 when the gas piston rod flange 39 contacts the shoulder 43 on the buffer piston rod. This point in the cycle is illustrated by FIGURE 2 of the drawings. Thereafter, the gas piston rod and the buffer piston rod will continue the initial stroke to the left. The floating piston 5 will tend to remain stationary with respect to the buffer piston rod until it is engaged by the piston rod llange 55, the position illustrated by FIGURE 3 of the drawings. The remainder of the'initial stroke is traversed with the oating piston being moved substantially free through the oil by virtue of the apertures 51 being uncovered and the enlarging clearance between the periphery of the piston and the cylinder wall occasioned by the tapered cylinder wall.

During the initial stroke of the gas piston 13 and its piston rod 15, the coil return spring 27 is compressed, the air in the coil spring chamber being exhausted through the ports 31. With the completion of the initial stroke portion of the cycle, the apparatus will assume the position of the parts as shown in FIGURE 4 of the drawings, and the counterstroke movement will take place. The first step in the counterstroke results in `the gas piston and its piston rod being moved under influence of the coil-spring in a direction to the right, as viewed in FIGURE 5 of the drawings. The gas piston rod flange 39 will move freely through the buffer piston rod 9 a substantial portion of the counterstroke and until a shoulder 63 of the slide 17 engages the end 65 of the buffer piston rod, the position of parts as shown in FIGURE 5 of the drawings. The counterstroke continues to the right and moves the buffer piston rod with it, the floating piston 5 remaining stationary until it is contacted by the buer piston rod flange 53. The ilange 53 being brought into engagement with the floating piston closes olf the piston apertures 51 thereby stopping the lluid 7 from flowing therethrough. Bulfer action is effected by the iluid oiering resistance to the floating piston and the increasing resistance resulting from the decreasing clearance between the periphery of the piston and the cylinder wall occasioned by the tapered cylinder wall. The parts will then continue to completion of the counterstroke to the battery position as shown in FIGURE l of the drawings, with the buffer gradually effecting buling action over a relatively short portion of travel and at the end of the counterstroke.

Thus, it will be recognized by those persons skilled in the art that the present invention provides a buffer for a reciprocating mechanism which is effective over a relatively short interval of tra-vel at the end of the return stroke. The arrangement is such that it not only effects eflicient butllng action, but also it effects this bufing action without producing energy losses during other parts of the cycle by being responsive only upon approach of the reciprocating .member to opposite limits of its travel. In view of this arrangement, it will become obvious also to those persons skilled in the art that a much shorter stroke is provided to effect buffer action which, ofcourse, enables a smaller buifer to be provided with consequent saving in space, reduction in weight, and reduction in cost. Furthermore, it will become apparent that the buffer of the present invention is capable of adaptation to applications other than the particular ordnance application herein disclosed. Although but a single embodiment of the present invention has been shown and described it will be recognized that other embodiments are possible. Therefore, it is desired that the present invention shall not be limited except insofar as is made necessary by the prior art and by the spirit of the appended claims.

What is claimed is:

1. A hydraulic energy absorption device for a reciprocating member comprising a stationary cylinder surrounding a portion of said reciprocating member, an annular piston rod slidably mounted on said reciprocating member disposed between said reciprocating member and said cylinder, a uid medium disposed within the area defined by said piston rod and the walls of said cylinder, an annular piston carried by said piston rod disposed within said fluid medium having apertured means comprising at least one opening therethrough responsive to offer substantially no resistance to fluid ow in the initial stroke of said reciprocating member, one-way -valve means carried by said piston rod disposed in association with said apertured means for opposing fluid flow through said apertured means in the counterstroke of said reciprocating member, and cooperative means on said reciprocating member and said piston rod responsive to the approach of said member to its extreme limits of movement for eiecting simultaneous movement of said piston rod with said member.

2. The invention as defined in claim 1 wherein said annular piston is disposed to provide a movable partition in said cylinder whereby the iiuid chamber is divided into separate compartments, and wherein a portion of the cylinder walls adjacent to said piston are tapered outwardly in the direction of the initial stroke of said reciprocating member.

3. The invention as defined in claim 2 wherein said` piston rod valve means comprises an annular ange on said piston rod extending radially outwardly therefrom and at least coextensive with said piston opening on the side thereof toward the extreme limit of said reciprocating member initial stroke.

4. A hydraulic type buffer for a reciprocating member having a rod-like portion, said buffer comprising a hollow cylindrical piston rod telescopically mounted on said rodlike portion, two outwardly extending projections carried by said rod-like portion in spaced apart relation, an inwardly extending projection carried by said piston rod disposed between said two outwardly extending projections, a stationary hydraulic cylinder surrounding said piston rod, a Ifluid medium contained in said cylinder, a oating piston carried by said piston rod disposed in said fluid medium and in association with said cylinder to provide separate uid chambers on opposite sides thereof, means providing free ow for said fluid medium from one chamber to the other comprising at least one aperture in said floating piston in communication with each one of said chambers, and means carried by said piston rod disposed in association with each said aperture responsive to engage said piston and close said aperture upon approach of said member to the counterstroke limit thereof.

5. The invention as dened in claim 4 wherein a portion of the cylinder walls adjacent to said piston are tapered outwardly in the direction of the initial stroke of said reciprocating member.

References Cited in the file of this patent UNITED STATES PATENTS 1,825,233 Joyce Sept. 29, 1931 v2,349,124 Trotter May 16, 1944 2,358,340 Lucht Sept. `19, 1944 2,713,401 Serste July 19,1955 

